Printers are useful for producing printed images of a wide range of types. Printers print on receivers (or “imaging substrates”), such as pieces or sheets of paper or other planar media, glass, fabric, metal, or other objects. Printers typically operate using subtractive color: a substantially reflective receiver is overcoated image-wise with cyan (C), magenta (M), yellow (Y), black (K), and other colorants. Various schemes can be used to process images to be printed.
For example, U.S. Publication No. 2008/0159786 by Tombs et al., entitled “Selective printing of raised information by electrography,” published Jul. 3, 2008, the disclosure of which is incorporated herein by reference, describes electrophotographic printing using marking particles of a substantially larger size than the standard size marking particles of the desired print image. Tombs et al. also describe using non-pigmented (“clear”) marking particles to overlay raised information on an image. This technique is very useful. However, not all jobs need raised information printed.
U.S. Pat. No. 5,111,302 to Chan et al., entitled “Method and system for enhancing the quality of both color and black and white images produced by ink jet and electrophotographic printers,” issued May 5, 1992, the disclosure of which is incorporated herein by reference, describes an embodiment of undercolor removal (UCR). This technique reduces the amount of toner consumed in printing near-neutrals by replacing black density formed with cyan, magenta, and yellow colorants with black colorant. The amount of UCR is specified using a percentage of the black density from the Y, M, and C to be replaced with K. However, this UCR method can reduce maximum density and thus degrade image quality.
U.S. Pat. No. 5,734,800 to Herbert et al., entitled “Six-color process system,” issued Mar. 31, 1998, the disclosure of which is incorporated herein by reference, describes UCR and gray component replacement (GCR). In GCR, black is used to replace a portion of the complementary toner to the color to be reproduced (e.g., with 100% GCR, red colors are made with Y, M, and K instead of Y, M, and C). The amount of GCR is specified using a percentage of the complementary toner to be replaced by black. Typical GCR percentages are from 30-50%. However, various schemes for performing GCR can result in more black toner being added to lower-density regions of the tonescale than desirable, resulting in reduced image quality.
A print job, i.e., a set of job data to be reproduced onto one or more pages of output, can include multiple types of content. An example of a job is a page of a newspaper, which contains text, halftoned photographs, and line-art or other graphics. Various techniques are used to process different content types within a single job, and any given printer is generally designed to produce higher-quality output for some types of content than for others.
For example, U.S. Publication No. 2006/0114481 by Moore, entitled “Object-oriented ink selection,” published Jun. 1, 2006, describes processing print job data based on objects identified in the job. For example, a block of text is an object and a photographic image is a different type of object. For each object, a black colorant selection is made among matte and gloss finish single component black colorant formulations based on determined object type. For example, text is printed with matte black, and photographs are printed with glossy black.
U.S. Pat. No. 5,704,021 to Smith et al., entitled “Adaptive Color Rendering By An Inkjet Printer Based On Object Type,” issued Dec. 30, 1997, likewise describes changing the halftone or color matching of an object in a job depending on the type of job.
However, these systems are only concerned with the appearance of individual objects and not with the overall quality or viewer impression of the printed job. Moreover, this scheme does not take into account the characteristics of the receiver on which the image will be printed, or of the type of job (e.g., 4″×6″ photograph) being printed.
U.S. Pat. No. 6,542,173 to Buckley, entitled “Systems, Methods And Graphical User Interfaces For Printing Object Optimized Images Based On Document Type,” issued Apr. 1, 2003, describes identifying a job with the predominant object type in that job. All objects in that job can be rendered according to the identified predominant type, or two or more sets of rendering parameter options can be applied to different types of objects of a document, based on the identified document type. However, rendering all objects with a single type produces lower-quality renderings of objects that are not actually that type. Changing rendering parameter options based on the object type and the page type still does not take into account the appearance of the whole page.